Certain change gear transmissions have utilized X-control mechanisms for a number of years. In change gear transmission art, an X-control mechanism is a mechanism that reverses the direction of linear motion of a pair of spaced-apart members by means of a pivotable arm pivotably mounted therebetween such that when one of the members moves in one direction to engage the pivotable arm on one side of the pivot point, the arm on the opposite side of the pivot point pivots and engages the other member and moves it in opposite direction of movement of the first member. Such is of particular advantage in application to gear shaft patterns for it enables, one for example, to move a gear shift arm to a selected location in the shifting pattern which then, by means of the pivot arm, causes a clutching mechanism to move in an opposite direction to clutchingly engage a mainshaft gear to the transmissions mainshaft to provide a desired gear change ratio.
Such X-control mechanisms are costly and complex and have heretofore employed a bolt having a threaded end and substantially cylindrical pivot surface along its shank about which the pivot arm pivots once mounted on the transmission housing.
Generally, the bolt has been inserted through aligned openings through the pivot arm and transmission housing from inside the transmission housing such that the enlarged head of the bolt rests against the pivot arm inside the transmission housing with the threaded end of the bolt exposed in the outside of the transmission housing and onto which is threaded a nut washer combination for securing the bolt to the housing. The pivot surface has a larger diameter than the threaded end to provide an annular shoulder on the bolt facing towards the threaded end that engages the inside of the housing when the bolt shank is inserted through the opening through the pivot arm.
The problems with the use of a nut/bolt combination is that, unless the nut is wired or otherwise secured, there is no assurance that the nut will not loosen over a period of time in addition to the assembly of the parts itself being difficult in having to hold the bolt steady while tightening the nut.
The present invention eliminates the use of such prior art bolt and nut combination for mounting the pivotable arm of the X-control mechanism to the transmission housing by eliminating both the nut and the threads and replacing them with a pivot pin having an enlarged head and a transverse annular groove in the outer surface at the exposed end of the shank that is positioned such that a retaining ring such as a snap ring can be inserted into the groove and hold the pivot arm against the transmission housing without inhibiting its ability to pivot.